A semiconductor device includes a substrate, a trench in the substrate, the trench having an inclined sidewall, a reflective layer over the inclined sidewall, a grating structure over the substrate, and a waveguide in the trench. The waveguide is configured to guide optical signals between the grating structure and the reflective layer.
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15. A method of manufacturing a semiconductor device, the method comprising:
providing a semiconductor substrate;
etching the semiconductor substrate to form an opening in the semiconductor substrate, a sidewall of the opening having a top portion and a bottom portion, wherein an angle between the sidewall and the semiconductor substrate is between 40 degrees and 50 degrees, wherein the top portion is laterally offset from the bottom portion;
depositing a reflector to cover the top portion and the bottom portion, the reflector having at least 90% reflectivity;
forming a grating structure over the semiconductor substrate, the grating structure comprising a plurality of facets angled relative to each other to form a plurality of teeth;
after depositing the reflector, forming a waveguide in the opening to guide optical signals between the grating structure and the reflector, the waveguide comprising a core layer and a cladding layer, a refractive index difference between the core layer and the cladding layer being in the range from 0.05 to 1; and
mounting an optical component over the semiconductor substrate, the optical component being a light emitting device or a light detecting device.
8. A method of manufacturing a semiconductor device, the method comprising:
etching a substrate to form a trench in the substrate, the trench having an inclined sidewall, an angle between the inclined sidewall and a plane of the substrate being between 40 degrees to 50 degrees, the inclined sidewall extending from a top surface of the substrate into the substrate;
forming a dielectric material in the trench;
etching the dielectric material to form a grating structure in the dielectric material, the grating structure being located in a first portion of the trench, the grating structure being level with the inclined sidewall, the grating structure including facets oriented in a direction closer to a normal direction of the top surface of the substrate than the inclined sidewall;
forming a reflective layer over the inclined sidewall, the reflective layer having at least 90% reflectivity; and
forming a waveguide in a second portion of the trench, the waveguide comprising a core layer and a cladding layer, a refractive index difference between the core layer and the cladding layer being in the range from 0.05 to 1; and
mounting an optical component over the substrate, the optical component being a light emitting device or a light detecting device, wherein the grating structure, the waveguide, the reflective layer and the optical component are arranged along an optical path.
1. A method of manufacturing a semiconductor device, the method comprising:
etching a substrate to form a trench in the substrate, the trench extending from a top surface of the substrate into the substrate, the trench having an inclined sidewall, an angle between the inclined sidewall and a plane of the substrate being between 40 degrees to 50 degrees;
etching the substrate to form a grating structure in the substrate, at least a portion of the grating structure being level with the inclined sidewall, the grating structure including facets oriented in a direction closer to a normal direction of the top surface of the substrate than the inclined sidewall;
forming a reflective layer over the inclined sidewall, the reflective layer having at least 90% reflectivity and wherein forming the reflective layer over the inclined sidewall comprises:
forming a dielectric layer over the substrate, the dielectric layer continuously extending over the inclined sidewall, a bottom of the trench, and the facets of the grating structure;
forming a reflective material over the dielectric layer, the reflective material continuously extending over the inclined sidewall, the bottom of the trench and the facets of the grating structure; and
removing the reflective material from the bottom of the trench, the reflective material remaining over the inclined sidewall defining the reflective layer;
forming a waveguide in the trench, the waveguide comprising a core layer and a cladding layer, a refractive index difference between the core layer and the cladding layer being in the range from 0.05 to 1; and
mounting an optical component over the substrate, the optical component being a light emitting device or a light detecting device, wherein the grating structure, the waveguide, the reflective layer and the optical component are arranged along an optical path.
2. The method of
etching the substrate to form the trench in the substrate includes a wet etch; and
etching the substrate to form the grating structure in the substrate includes a dry etch.
3. The method of
4. The method of
5. The method of
forming a core layer over the dielectric layer in the trench; and
forming a cladding layer over the core layer to obtain the waveguide.
6. The method of
7. The method of
9. The method of
10. The method of
forming a dielectric layer over the substrate, the dielectric layer continuously extending over the inclined sidewall, a bottom of the trench, and the facets of the grating structure;
forming a reflective material over the dielectric layer, the reflective material continuously extending over the inclined sidewall, the bottom of the trench and the facets of the grating structure;
removing a portion of the reflective material, the reflective material remaining over the inclined sidewall defining the reflective layer, the reflective material remaining over the facets of the grating structure defining a further reflective layer for the grating structure;
forming a core layer over the dielectric layer in the trench; and
forming a cladding layer over the core layer to obtain the waveguide.
11. The method of
12. The method of
13. The method of
14. The method of
18. The method of
19. The method of
20. The method of
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This application is a division of U.S. application Ser. No. 14/102,605, entitled “Semiconductor Device and Method of Manufacturing,” filed on Dec. 11, 2013, which application is hereby incorporated herein by reference.
As integrated circuits (ICs) become increasingly smaller and faster, electrical signals used in various types of ICs are also subject to increasing delays caused by capacitance, inductance, or resistance in the ICs. At a certain high speed and/or frequency, such delays become a design concern. To avoid potential signal delay issues, optical signals are used instead of electrical signals for data transmission in some situations.
One or more embodiments are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout. The drawings are not to scale, unless otherwise disclosed.
It is to be understood that the following disclosure provides many different embodiments or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. An inventive concept may; however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. It will be apparent; however, that one or more embodiments may be practiced without these specific details. Like reference numerals in the drawings denote like elements.
In some embodiments, a semiconductor device comprises a substrate and a grating structure over the substrate. The substrate further has a trench with an inclined sidewall. A reflective layer is over the inclined sidewall. A waveguide is in the trench between the reflective layer and the grating structure. In at least one embodiment, the grating structure is configured to multiplex (also referred to as “mux”) and/or demultiplex (also referred to as “demux”) optical signals. The waveguide is configured to guide optical signals between the grating structure and the reflective layer. The reflective layer is configured to direct optical signals demuxed, or to be muxed, by the grating structure between the waveguide and external optical circuitry located out of a plane of the waveguide. As a result, one or more embodiments optical routing and wavelength multiplexing/demultiplexing are integrated in a single substrate. In at least one embodiment, the resulting semiconductor device includes a wavelength-division multiplexing (WDM) demultiplexer and/or multiplexer which has a low profile and/or configuration flexibility for operation over a wide range of wavelengths, without being limited to a specific range of wavelengths and/or a specific substrate structure as in other approaches.
In some embodiments, the substrate no includes a silicon carbide (SiC) substrate, sapphire substrate, a silicon (Si) substrate or a glass substrate. In at least one embodiment, the substrate no includes one or more electrical components. Examples of electrical components include, but are not limited to, resistors, capacitors, inductors, diodes, field effect transistors (FETs), metal-oxide-semiconductor FETs (MOSFETs), complementary metal-oxide-semiconductor (CMOS) transistors, and bipolar transistors.
The trench 120 includes an inclined sidewall 122 and a bottom 124. In some embodiments, an angle α between the inclined sidewall 122 and a plane of the substrate no is in the range from 40 degrees to 50 degrees. In at least one embodiment, the angle α is 45 degrees. The inclined sidewall 122 is formed in one or more embodiments by a wet etch as described herein. A reflective is over the inclined sidewall 122. Example reflective materials of the reflective layer 126 include, but are not limited to, Cu, Au, Ag, Al, and Ti. In at least one embodiment, the reflective layer 126 includes a multi-layered structure in which dielectrics of high and low refractive indices are arranged alternatingly. In at least one embodiment, the reflective layer 126 has a thickness of at least 50 nm and/or at least 90% reflectivity at selected wavelengths.
The grating structure 130 in one or more embodiments includes a plurality of facets 132 arranged successively along a line 134 concaved inward of a block 136. The adjacent facets 132 are angled relative to each other to form a plurality of “teeth” of the grating structure 130. The facets 132 are oriented in a direction closer to a normal direction Z of the substrate no than the inclined sidewall 122. In at least one embodiment, an angle between the facets 132 and the plane of the substrate no is in the range from 85 degrees to 95 degrees. In at least one embodiment, the angle is 90 degrees for one or more facets 132 which extend vertically or normally to the plane of the substrate no. In some embodiments, the facets 132 of the grating structure 130 are formed in the block 136 by a dry etch as described herein. In at least one embodiment, the block 136 includes an integral part of the substrate no. For example, the facets 132 of the grating structure 130 are formed in a sidewall other than the inclined sidewall 122 of the trench 120. In at least one embodiment, the block 136 includes a dielectric material deposited over the substrate no, and the facets 132 of the grating structure 130 are formed in a sidewall of the dielectric material block 136. In some embodiments, a reflective layer (not shown in
The waveguide 140 includes a core layer 141 over the bottom 124 of the trench 120, and a cladding layer 142 (also referred to as “top cladding layer”) over the core layer 141. In at least one embodiment, the substrate no at the bottom 124 of the trench 120 defines a bottom cladding layer for the waveguide 140. In at least one embodiment, a dielectric layer (not shown in
The optical component 150 is configured to process, receive and/or transmit optical signals. Examples of the optical component 150 include, but are not limited to, light emitting devices such as lasers and light emitting diodes, light detecting devices such as photo-sensors, optical modulators, and optical couplers. In at least one embodiment, the optical component 150 includes at least one light source, such as an array of vertical cavity surface emitting laser (VCSEL). In at least one embodiment, the optical component 150 includes at least one optical sensor, such as an array of photo diodes.
In at least one embodiment, the semiconductor device 100 includes an optical port 143 for input and/or output of optical signals to and/or from the waveguide 140. For example, the optical port 143 includes an exposed end of the waveguide 140 on an edge of the substrate no. An end of an external optical fiber is attachable to the optical port 143. A multi-wavelength optical signal (also referred to herein as “multiplexed optical signal”) 144 is inputted into and/or outputted from the waveguide 140 via the optical port 143. In at least one embodiment, a lens (not shown in
In one or more embodiments, the semiconductor device 100 includes a WDM demultiplexer. A multiplexed optical signal 144 is inputted into the waveguide 140 via the optical port 143. The multiplexed optical signal 144 is guided along a first portion 145 of the waveguide 140 toward the grating structure 130. The grating structure 130 demuxes the multiplexed optical signal 144 into a plurality of optical signals 146H, 147H, 148H having corresponding different wavelengths, and sends the optical signals 146H, 147H, 148H in corresponding different directions along a second portion 149 of the waveguide 140 toward the reflective layer 126 on the inclined sidewall 122. The optical signals 146H, 147H, 148H are reflected by the reflective layer 126, out of a plane of the waveguide 140, as optical signals 146V, 147V, 148V directed at the optical component 150. The optical component 150 includes at least one optical sensor configured to convert the received optical signals 146V, 147V, 148V into electrical signals to be processed by other circuitry of the optical component 150, or to be communicated out of the optical component 150.
In one or more embodiments, the semiconductor device 100 includes a WDM demultiplexer. A multiplexed optical signal 144 is inputted into the waveguide 140 via the optical port 143. The multiplexed optical signal 144 is guided along a first portion 145 of the waveguide 140 toward the grating structure 130. The grating structure 130 demuxes the multiplexed optical signal 144 into a plurality of optical signals 146H, 147H, 148H having corresponding different wavelengths, and sends the optical signals 146H, 147H, 148H in corresponding different directions along a second portion 149 of the waveguide 140 toward the reflective layer 126 on the inclined sidewall 122. The optical signals 146H, 147H, 148H are reflected by the reflective layer 126, out of a plane of the waveguide 140, as optical signals 146V, 147V, 148V directed at the optical component 150. The optical component 150 includes at least one optical sensor configured to convert the received optical signals 146V, 147V, 148V into electrical signals to be processed by other circuitry of the optical component 150, or to be communicated out of the optical component 150. The optical component iso, the reflective layer 126, the grating structure 130 and the waveguide 140 are arranged along an optical path of the semiconductor device 100 as described.
In one or more embodiments, the semiconductor device 100 includes a WDM multiplexer. The optical component 150 includes at least one light source configured to emit optical signals 146V, 147V, 148V toward the reflective layer 126 on the inclined sidewall 122. The optical signals 146V, 147V, 148V are reflected by the reflective layer 126 as optical signals 146H, 147H, 148H which are guided along the second portion 149 of the waveguide 140 to the grating structure 130. The grating structure 130 muxes the optical signals 146H, 147H, 148H into the multiplexed optical signal 144 and sends the multiplexed optical signal 144 along the first portion 145 of the waveguide 140 toward the optical port 143 to be communicated to external optical circuitry.
In some embodiments, optical routing and wavelength multiplexing/demultiplexing are integrated in a single substrate of a semiconductor device as described herein. As a result, the semiconductor device, which is one or more embodiments includes a WDM demultiplexer and/or WDM multiplexer, has a low profile. Additionally or alternatively, in one or more embodiments appropriate materials for the waveguide are selected depending on the wavelengths of the optical signals to be transmitted, received and/or processed by the semiconductor device. For example, when the optical signals are in the visible light wavelength range, materials transparent to the visible light are selected for at least the core layer of the waveguide. In another example, when the optical signals are in the IR wavelength range, materials transparent to the IR light are selected for at least the core layer of the waveguide. Such flexibility permits the semiconductor device in accordance with some embodiments to be configured for operation in a wide range of wavelengths. In contrast, other approaches exhibit potential limitations in the operational range of wavelengths. For example, some other approaches include a waveguide in a Si substrate of a Silicon-On-Insulator (SOI) structure. Because Si has a low transparency to visible and/or IR light, devices based on the other approaches are not operable in the visible and/or IR light wavelength range. Compared to the other approaches, some embodiments provide greater flexibility in configuration and/or operational wavelength range of the semiconductor device. Although at least one embodiment includes an SOI structure as the substrate, other embodiments are not limited to substrates based on SOI structures.
The semiconductor device 200 comprises a substrate 210 having a trench 220, a grating structure 230, a waveguide 240 and an optical component 250. The trench 220 has an inclined sidewall 222 and a bottom 224. A dielectric layer 225 is over the inclined sidewall 222, the bottom 224 and the grating structure 230. A reflective layer 226 is over the dielectric layer 225 overlying the inclined sidewall 222. The grating structure 230 is in another sidewall 227 of the trench 220. The grating structure 230 includes a plurality of facets 232 (one of which is schematically illustrate in
In at least one embodiment, the substrate 210 includes a Si substrate. The trench 220 has a depth of more than 30 μm in some embodiments.
The dielectric layer 225 defining the bottom cladding layer comprises at least one of SiO2 or SiON formed by plasma-enhanced chemical vapor deposition (PECVD) in some embodiments. In one or more embodiments, spin-on dielectrics or polymers are used to form the bottom cladding layer. The thickness of the bottom cladding layer is at least 500 nm in some embodiments to prevent optical leak. The core layer 241 comprises at least one of SiON or SiN formed by PECVD in some embodiments. In one or more embodiments, spin-on dielectrics or polymers are used to form the core layer 241. The thickness of the core layer 241 is at least 15 μm in some embodiments. The top cladding layer 242 comprises at least one of SiO2 or SiON formed by PECVD in some embodiments. In one or more embodiments, spin-on dielectrics or polymers are used to form the top cladding layer 242. The thickness of the top cladding layer 242 is at least 500 nm in some embodiments to prevent optical leak. In some embodiment, an optical fiber is placed in the trench 220 as the waveguide 240.
In at least one embodiment, at least one of the reflective layer 226 or the reflective layer 237 includes at least one selected from the group consisting of Cu, Au, Ag, Al, and Ti, and/or has a thickness of at least 50 nm. In at least one embodiment, the reflective layer 226 and the reflective layer 237 include the same reflective material.
The RDL 252 is electrically connected to one or more electrical components included in the semiconductor device 100. For example, the electrical components are formed in the substrate In some embodiments, the RDL 252 comprises Al, Cu, or another electrically conductive material, and/or has a thickness of at least 1 μm.
In at least one embodiment, a passivation layer (not shown in
In at least one embodiment, an under bump metallization (UBM) layer (not shown in
The solder bump 254 is formed over the UBM layer and comprises lead-free solder or gold bumps in some embodiments. In at least one embodiment, the solder bump 254 comprises micro bumps for flip-chip bonding with the optical component 250. The overall thickness for the UBM layer and the solder bump 254 is in the range from 1 μm to 15 μm in some embodiments.
In some embodiments, one or more through substrate vias (TSVs) (not shown in
In at least one embodiment, the semiconductor device 200 operates in a manner similar to that described with respect to the semiconductor device 100. For example, a multiplexed optical signal is input via the waveguide 240 to the grating structure 230, which demuxes the multiplexed optical signal into a plurality of demuxed optical signals having different wavelengths. One of the demuxed optical signals is denoted as 248H in
As shown in
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During the wet etching, in some embodiments, the etching mask 464 is partially etched, widening the exposed portion of the substrate 410 and resulting in a larger trench 420 than the original exposed region 439. In some embodiments, the wet etching process of
As shown in
At operation 505, a trench having an inclined sidewall is etched in a substrate. For example, as shown in
At operation 515, a grating structure is etched in the substrate. For example, as shown in
At operation 525, a reflective layer is formed over the inclined sidewall of the trench. For example, as shown in
As shown in
As shown in
At operation 535, a waveguide is formed in the trench. For example, as shown in
At operation 545, an optical component is mounted over the substrate. For example, as show in
As shown in
In one of more embodiments described herein, the grating structure is formed by etching the substrate, e.g., the Si substrate. Other configurations of and/or methods for forming grating structures are within the scope of various embodiments. For example, in at least one embodiment described herein, a grating structure is formed by etching a block of dielectric material formed over the substrate.
As shown in
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At operation 805, a trench having an inclined sidewall is etched in a substrate. For example, as shown in
At operation 815, a dielectric material is formed in the trench. For example, as shown in
At operation 825, a grating structure is etched in the dielectric material. For example, as shown in
At operation 835, a reflective layer is formed over the inclined sidewall of the trench. For example, as shown in
As described with respect to
At operation 845, a waveguide is formed in a second portion of the trench. For example, as shown in
At operation 855, an optical component is mounted over the substrate. For example, as shown in
The above methods include example operations, but they are not necessarily required to be performed in the order shown. In some embodiments, operations may be added, replaced, changed order, and/or eliminated as appropriate, in accordance with the spirit and scope of embodiments of the disclosure. Embodiments that combine different features and/or different embodiments are within the scope of the disclosure and will be apparent to those of ordinary skill in the art after reviewing this disclosure.
According to some embodiments, a semiconductor device comprises a substrate, a trench in the substrate, the trench having an inclined sidewall, a reflective layer over the inclined sidewall, a grating structure over the substrate, and a waveguide in the trench. The waveguide is configured to guide optical signals between the grating structure and the reflective layer.
In a method of manufacturing a semiconductor device in accordance with some embodiments, a trench is etched in a substrate, the trench having an inclined sidewall. A grating structure is etched in the substrate. The grating structure is at least partially co-elevational with the inclined sidewall. The grating structure includes facets oriented in a direction closer to the normal direction of the substrate than the inclined sidewall. A reflective layer is formed over the inclined sidewall. A waveguide is formed in the trench. An optical component is mounted over the substrate. The grating structure, the waveguide, the reflective layer and the optical component are arranged along an optical path.
In a method of manufacturing a semiconductor device in accordance with some embodiments, a trench is etched in a substrate, the trench having an inclined sidewall. A dielectric material is formed in the trench. A grating structure is etched in the dielectric material, the grating structure located in a first portion of the trench. The grating structure is at least partially co-elevational with the inclined sidewall. The grating structure includes facets oriented in a direction closer to the normal direction of the substrate than the inclined sidewall. A reflective layer is formed over the inclined sidewall. A waveguide is formed in a second portion of the trench. An optical component is mounted over the substrate. The grating structure, the waveguide, the reflective layer and the optical component are arranged along an optical path.
It will be readily seen by one of ordinary skill in the art that one or more of the disclosed embodiments fulfill one or more of the advantages set forth above. After reading the foregoing specification, one of ordinary skill will be able to affect various changes, substitutions of equivalents and various other embodiments as broadly disclosed herein. It is therefore intended that the protection granted hereon be limited only by the definition contained in the appended claims and equivalents thereof.
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